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The video shows stable hover a novel Vertical Take-Off and Landing (VTOL) aircraft -- the Cyclocopter, developed at the University of Maryland by Dr. Moble Benedict, Mr. Matthew Westerfield, Dr. Vikram Hrishikeshavan and Prof. Inderjit Chopra. Pilot for the present flight is Mr. Shane Boyer who is a graduate student at the University of Maryland.

Cyclocopter utilizes cycloidal-rotors (cyclorotors), a revolutionary horizontal axis propulsion concept which has many advantages such as higher aerodynamic efficiency and maneuverability. One of the key advantages of the cyclorotor is its thrust vectoring capability, which is utilized in the present study for yaw control. The present vehicle has a twin-cyclorotor and a horizontal tail rotor configuration where each of the rotors is powered using independent motors.

The cyclorotor design was optimized based on the detailed experimental studies conducted by Dr. Moble Benedict, Mr. Tejaswi Jarugumilli and Prof. Inderjit Chopra. A novel attitude control technique is developed using differential RPM control and thrust vectoring of the cyclorotors for rolling and yawing, and horizontal tail rotor for pitch control. For closed-loop attitude stabilization of the vehicle, a proportional-derivative controller was implemented on an onboard 1.5 gram processor-sensor board. Using this control system, the stable autonomous hover of the cyclocopter was successfully demonstrated.

The video shows stable hover of a novel Vertical Take-Off and Landing (VTOL) aircraft -- the Cyclocopter, developed at the University of Maryland by Dr. Moble Benedict, Mr. Joseph Mullins, Dr. Vikram Hrishikeshavan and Prof. Inderjit Chopra.

Cyclocopter utilizes cycloidal-rotors (cyclorotors), a revolutionary horizontal axis propulsion concept which has many advantages such as higher aerodynamic efficiency and maneuverability. One of the key advantages of the cyclorotor is its thrust vectoring capability, which is utilized in the present study for yaw control. The present vehicle has a quad-cyclorotor configuration where each of the rotors is powered using independent motors. Also by using separate thrust vectoring mechanisms for each rotor, each of the thrust vectors could be independently tilted making the vehicle extremely maneuverable.

The cyclorotor design was optimized based on the detailed experimental studies conducted by Dr. Moble Benedict, Mr. Tejaswi Jarugumilli and Prof. Inderjit Chopra. A novel attitude control technique is developed using differential RPM control and thrust vectoring which is also designed to take care of the inherent pitch-roll couplings. For closed-loop attitude stabilization of the vehicle, a proportional-derivative controller was implemented on an onboard 3 gram processor-sensor board. Using this control system, the stable autonomous hover of the cyclocopter was successfully demonstrated. This is the first pure cyclocopter (entire thrust produced from cyclorotors) in the history to perform stable controlled hover after the inception of this concept 100 years back.

The video shows stable forward flight of a novel Vertical Take-Off and Landing (VTOL) aircraft -- the Cyclocopter, developed at the University of Maryland. Forward flight control strategies were developed and implemented by Ms. Elena Shrestha, Dr. Moble Benedict, Dr. Vikram Hrishikeshavan and Prof. Inderjit Chopra.

Cyclocopter utilizes cycloidal-rotors (cyclorotors), a revolutionary horizontal axis propulsion concept which has many advantages such as higher aerodynamic efficiency, maneuverability, and high gust tolerance. In addition, the cyclocopter is capable of maintaining steady, level flight in a power efficient manner. Unlike a conventional helicopter, the forward flight of a cyclocopter is performed purely utilizing thrust vectoring (varying cyclic pitch phasing) and not by pitching the entire vehicle forward. This is the first time the forward flight capability of a cyclocopter is demonstrated by purely thrust vectoring and not pitching the vehicle forward.

The world’s smallest cycloidal-based rotorcraft, or cyclocopter, has been recently designed, built and test flown successfully at Texas A&M University, Advanced Vertical Flight Laboratory under the direction of Dr. Moble Benedict, with graduate students Carl Runco and David Coleman. Weighing only 29 grams, it utilizes the latest advances in microelectronics technology and carbon fiber composite construction, as well as extensive experimental data for design and optimization.

The cyclorotor, unlike traditional helicopter rotors, utilizes a horizontal axis of rotation with the blade span parallel to this axis. With the blades cyclically pitched such that each blade has a positive geometric angle of attack at the top and bottom of the circular trajectory, a net thrust is produced. The mechanism that generates this pitching motion allows complete 360 degree thrust vectoring capabilities, one major advantage of the cyclocopter which allows the vehicle to fly in flight regimes unsuitable for traditional helicopters and multi-copters. Additionally, recent studies have shown that a cyclorotor can achieve higher hover efficiency than a conventional rotor at smaller scales, because of uniform lift distribution and favorable unsteady aerodynamic environment along the blade span. For these reasons, the cyclocopter is advantageous for applications such as search and rescue operations and indoor to outdoor surveillance and reconnaissance in which high hover efficiency, agility and gust-tolerance are needed.

The current vehicle prototype utilizes cantilevered rotor blades with a semi-elliptical planform shape, resulting in a novel, lightweight cyclorotor design. To minimize blade bending, a unique, high strength-to-weight ratio unidirectional carbon-fiber based structural design is employed, and the blades are fabricated using a specialized manufacturing process which ensures consistency and lightweight results (0.12 grams each). During flight, roll is controlled by varying the differential rotational speed of the main cyclorotors, which generates a lift imbalance about the longitudinal axis of the vehicle. Pitch is controlled by changing the tail rotor RPM, which, due to the variation in vertical thrust, creates a moment about the pitching axis. Finally, yaw is controlled by tilting one cyclorotor thrust vector forward and the other backward. Additionally, both can be tilted in the same direction for forward or backward translation. Therefore, unlike a traditional hybrid aircraft such as a tilt-rotor, a cyclocopter can transition from hover to high-speed forward flight without any configuration change due to its thrust vectoring capability. A closed-loop proportional-derivative control strategy is implemented on a custom-built 1.3 gram autopilot which senses the vehicle motion and corrects the motor RPMs and tilts the thrust vectors accordingly. By careful tuning of feedback gains the vehicle has demonstrated stable hovering flight.